Breathing masks may be used to deliver gases of controlled composition, at a controlled pressure, and at a controlled flow to a person's face for inhalation. Gas composition typically is controlled to achieve a particular medical goal, such as anesthesiology. Gas pressure typically is controlled to ease or assist the breathing process, made difficult for example due to high altitude or a medical condition afflicting the user.
The breathing masks are used to apply continuous positive airway pressure (“CPAP”) treatment for sleep disorders, such as obstructive sleep apnea. Pursuant to this treatment the user wears a breathing mask while sleeping. A device delivers air to the breathing mask at a pressure above atmospheric pressure. This helps the user to breath more normally during sleep. Further descriptions of CPAP treatments and devices can be found in U.S. Pat. Nos. 5,199,424 and 5,433,193, which are hereby fully incorporated by reference.